Recently in the fiber industry, especially the synthetic fiber industry, the yarn treating speed has been increased very much, and it is usual that the treating speed of a synthetic multifilament yarn is equal to or more than 2500 m/min. When a yarn is treated at such a high speed, a certain operation which has conventionally been effected on a yarn without causing any trouble at a relatively low speed, cannot be carried out during a high speed winding operation. For example, it is very difficult to thread a yarn, which is delivered at a speed equal to or higher than 2500 m/min from a godet roller on a bobbin rotatably supported on a winding apparatus without causing any entanglement of the yarn around the godet roller. The reason will be explained hereinbelow. To obtain a package having a good shape by winding a yarn delivered at a high speed on a bobbin, it is very important that the winding angle, contacting pressure between the bobbin and friction roller, and the tension in the delivered yarn are properly adjusted, and it is well known that the tension in the yarn wound on a bobbin has an influence upon the shape of the obtained yarn package. Accordingly, to obtain a good wound package shape, it is required that a yarn is wound on a bobbin at a tension in the yarn as low as possible. However, when a yarn delivered at a low tension is threaded on a bobbin, there is a tendency that trouble occurs wherein the threading of the yarn fails frequently, because the yarn slack takes place temporarily at a portion between the lowermost godet roller and the winding apparatus, and as a result, the yarn entangles around the godet roller.
To obviate the above-mentioned trouble, the inventors of the present invention effected careful research regarding the mechanism of the entanglement of the yarn around the godet roller. They have found that the trouble does not occur if the temporarily lowered tension in the yarn upon threading is transmitted beyond the godet roller to upstream of the godet roller. However, it should be noted that the godet roller has a function in that it delivers a yarn at a constant speed while the yarn is normally being wound.